灌丛群落叶功能型及其与凋落物水分涵养性能的关系——以广西三种典型灌丛群落为例

牡荆、红背山麻杆和羊蹄甲群落是三种在广西壮族自治区具有较为重要水土保持功能的典型灌丛。通过野外勘察选择了受干扰程度较低的群落作为研究样地。通过测定样方中优势物种的叶功能性状和凋落物的水分涵养特征,揭示了灌丛群落的叶功能型及其与凋落物水分涵养性能的关系,以求更好地发挥灌丛在区域退化生态系统中生态恢复和水土保持的作用。研究结果表明,(1)三种灌丛群落的叶功能性状有着十分明显的差异,群落的叶功能型因此而分化形成了以羊蹄甲为代表的低干物质、低有机质与高比叶面积(低LOMC+LDMC-高SLA)的类型,以及以红背山麻杆群落和牡荆灌丛群落为代表的高干物质、高有机质与低比叶面积(高LDMC+LOMC-低SLA)的类型。后者因叶片磷含量(LPC)的不同,再进一步分化。(2)三种灌丛群落凋落物的水分涵养性能由于群落凋落物的水分涵养特征存在显著差异出现分化。红背山麻杆和牡荆灌丛的凋落物蓄积量(LS)和自然含水率(NWC)显著高于羊蹄甲灌丛,而它们的最大持水率(MWHR)则低于羊蹄甲灌丛。红背山麻杆和牡荆灌丛的最大拦蓄量(MIC)和有效拦蓄量(EIC)因此而显著高于羊蹄甲灌丛。(3)灌丛群落的叶功能性状SLA、LDMC、LOMC、LPC等分别与MIC和EIC等水分涵养性能特性存在显著相关性。叶功能型为低LDMC+LOMC-高SLA的羊蹄甲灌丛群落具有较低的水分涵养性能,而叶功能型为高LDMC+LOMC-低SLA的红背山麻杆和牡荆灌丛群落具有较高的水分涵养性能。为了提高生态系统的水土保持功能,在进行退化生态系统生态恢复时应尽可能选择叶功能型为高LDMC+LOMC-低SLA的群落类型。

Leaf functional types of shrub communities and their relationship with water conservation of litter: a case study of three typical shrub communities in Guangxi

Ass. Vitex negundo, Ass. Alchornea trewioides, and Ass. Bauhinia purpurea, three typical shrub communities distributing in the Guangxi Zhuang Autonomous Region, play an important role in soil and water conservation. Communities with relatively low disturbance were selected as study plots through field surveys in this region. The leaf functional traits of dominant species and the water conservation characteristics of litter in each quadrat were measured. The leaf functional type of shrub communities and their relationship with water conservation were revealed to better play the role of shrub communities in ecological restoration and soil and water conservation of degraded regional ecosystems. Results showed that: (1) There were significant differences in leaf functional traits among three shrub communities. The shrub communities differentiated into two leaf functional categories as a result: one type was represented by Ass. B. purpurea associated with low dry leaf matter and organic matter and high specific leaf area (low LOMC+LDMC-high SLA). Another type was represented by Ass. A. trewioides and Ass. V. negundo associated with high dry leaf matter and organic matter and low specific leaf area (high LDMC+LOMC-low SLA). Ass. A. trewioides and Ass. V. negundo further differentiated due to difference in leaf phosphorus content (LPC). (2)The water conservation performance of community litter was also differentiated among three shrub communities due to significant differences in water conservation characteristics of litter. The litter storage (LS) and natural water content (NWC) of Ass. A. trewioides and Ass. V. negundo were significantly higher than Ass. B. purpurea, while their maximum water holding rate (MWHR) was significantly lower than Ass. B. purpurea. The maximum interception capacity (MIC) and effective interception capacity (EIC) of Ass. A. trewioides and Ass. V. negundo therefore were significantly higher than that of Ass. B. purpurea. (3) The leaf functional traits of shrub community, such as SLA, LDMC, LOMC and LPC, were significantly correlated with the characteristics of water conservation performance, including MIC and EIC, respectively. The leaf functional type associated with low LDMC+LOMC-high SLA representing by Ass. B. purpurea had lower water conservation performance, while the leaf functional type associated with high LDMC+LOMC-low SLA representing by Ass. A. trewioides and Ass. V. negundo had higher water conservation performance. In order to improve the soil and water conservation function of ecosystems, community types with high LDMC+LOMC-low SLA leaf functional type should be adopted as much as possible to restore degraded ecosystems.